We have observed that the retina conserves omega 3 polyunsaturated fatty acids during polyunsaturated fatty acid deficiency. To us this implies that polyunsaturates are involved in maintaining a functional rod membrane. It is important to know how the retina holds on to its polyunsaturates and why they are necessary for this particular membrane system, since other membranes seemingly can get along without them. If we can answer these questions, we may be a step closer to explaining the phenomenon of visual excitation at the molecular level. The specific aims of the proposed research are: (1) To deplete the polyunsaturates from the ROS of rats and study the effect of the altered structure on the structure, function, and biosynthesis of ROS membranes. (2) To determine the mechanism by which the retina conserves polyunsaturates during polyunsaturated fatty acid deficiency. (3) To examine the retinas of rats with a hereditary retinal dystrophy and determine if the loss of structural and functional integrity of their ROS results from their inability to accumulate polyunsaturates and incorporate them into their ROS phospholipids.